Table 671

Age-related changes in human retinas harvested from patients of different ages: Values of quantitative analysis of images and biochemical values of protein amount

Age-related Changes

Thickness of the retina °mm ± SEM ^Ganglion cells number mm2 ± SEM Capillaries number mm2 ± SEM Synaptic bodies area C.U. ± SEM Cellular processes area C.U. ± SEM Intercellular gaps area C.U. ± SEM Protein y/mg of fresh tissue ± SEM

42Ó i 34.2 413.5 i 32.3 3.Ó i 1.4 122.4 i 4.9 82.3 i 3.1 3Ó.4 i 2.5 92.1 1.8

2Ó1 i 18.9* 25Ó.2 i 2Ó.8* 1.8 i 1.2* 38.5 i 1.Ó* 13.1 i 1.5* 14.3 i 1.4* 78.3 ± 1.3*

"without the pigmented epithelium that is detectable from all remaining layers

*P< 0.001 old versus young n= number of retinas

C.U.= Conventional Units furnished and printed directly by analyzer (Leica 1997). ^Number of ganglion cells corresponds to the number of the optic nerve fibers.

Figure 67.2 Micro-anatomical details of the human retina harvested from a young donor (18 years) observed by scanning electron microscopy. The ganglion cell layer (G), bipolar cell layer (B) and photoreceptor cell layer (P) may be seen (magnification 1600x). Reproduced by permission of the Canadian Ophthalmolo-gical Society.

Figure 67.2 Micro-anatomical details of the human retina harvested from a young donor (18 years) observed by scanning electron microscopy. The ganglion cell layer (G), bipolar cell layer (B) and photoreceptor cell layer (P) may be seen (magnification 1600x). Reproduced by permission of the Canadian Ophthalmolo-gical Society.

In the human retina, all layers can be clearly discerned and easily defined on the basis of well-known observations using light microscopy (see Figure 67.1).

Moreover, aging induces a strong decrease of the whole thickness of the retina from 426 ± 34,2 mm in younger to 261 ± 18,9 mm in older (i.e., a decrease of about 40%) as reported in line 1 of Table 67.1. Line 2 shows a strong decrease of the ganglion cells. These cells are 413.5 ± 32.3/mm2 in the retinas of young humans and go down to 256.2 ± 26.8/mm2 in the retinas of old humans, a decrease of about 38%. At line 3 a strong decrease of the number of the capillaries is reported. The latter are 3.6 ± 1.4 C.U. in adult patients, and go down to 1.8 ± 1.2 C.U. in the old age-group, a decrease of about 50%. The synaptic bodies (Table 67.1, line 4) go down from 122.4 ± 4.9 to about 38.5 ± 1.6 C.U. (old) for each microscopic area observed. The cellular processes (Table 67.1, line 5) also show a reduction from 82.3 ± 3.1 to 13.1 ± 1.5 C.U. for each microscopic area observed. The intercellular connections decrease from 36.4 + 2.5 C.U. to 14.3 +1.4 C.U. The protein content is slightly reduced: 92.1 ± 1.8 mg/mg of fresh tissue in younger subjects in comparison to 78.7 ± 1.3 in older ones.

Figure 67.3 Scanning electron photomicrograph showing the outer as well as the inner segments of photoreceptors. Moreover, the external limiting membrane, the bipolar cell layer, and numerous capillaries can be distinguished. Samples of the human retina were harvested from an old donor (68 years old) (magnification 8000x). Reproduced by permission of Canadian Ophthalmological Society.

Figure 67.3 Scanning electron photomicrograph showing the outer as well as the inner segments of photoreceptors. Moreover, the external limiting membrane, the bipolar cell layer, and numerous capillaries can be distinguished. Samples of the human retina were harvested from an old donor (68 years old) (magnification 8000x). Reproduced by permission of Canadian Ophthalmological Society.

Figure 67.4 Scanning electron photomicrograph showing photoreceptor cells' outer segments. Samples of the human retina were harvested from an young donor (21 years old). The cellular matrix is sometimes crossed by intercellular connections. These structures are due to a collapsed inter-photo-receptor matrix, which normally fills the sub-retinal spaces. The apex of many photoreceptors can be observed (magnification 16.000x). Reproduced by permission of Canadian Ophthalmological Society.

Figure 67.4 Scanning electron photomicrograph showing photoreceptor cells' outer segments. Samples of the human retina were harvested from an young donor (21 years old). The cellular matrix is sometimes crossed by intercellular connections. These structures are due to a collapsed inter-photo-receptor matrix, which normally fills the sub-retinal spaces. The apex of many photoreceptors can be observed (magnification 16.000x). Reproduced by permission of Canadian Ophthalmological Society.

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